Interference when using digitone inputs Please Help


#1

Good evening.
Having recently purchased a pair of akg k712 headphones, they are revealing so much sound wise. However, they need more volume than my monitor and Shure headphones, and this has highlighted interference.
Having looked at the inputs into my DB4 Allen and Heath, I’ve narrowed it down to the inputs on the Digitone being the culprit; one of the inputs has a TS audio cable coming in from my DFAM. If I disconnect this cable, the interference goes.

I’ve tried 3 different cables but the interference remains.

I have two Octatracks and the Digitone going into the DB4 and none of them present this problem. If I really boost the volume, white noise appears as you’d expect. But the interference from the Digitone inputs is changing pitch and sounds like electrical interference.

I’m wondering if I need to look at the volumes at all the stages from the DFAM to the mixer and whether I’m increasing the noise floor incrementally.

The interference exists even when the cable is unplugged from the DFAM; simply having the cable in the Digitone is enough.

What should my next steps be?

Cheers guys.

Adam


#2

Morning everyone.
I would really appreciate some to pointers from someone who knows what could be the cause of this.
Cheers. Adam


#3

Is the DFAM connected to the Digitone or to the mixer?

There is a quite high gain on the analog inputs of the Digitone possible. Reducing the input level settings in the Digitone to ~ 30 should give already enough level and could reduce your noise.

Are you using balanced connections from the Digitone to the mixer?


#4

Hi Chiron.
Thanks for your response.
The cables from the Digitone are unbalanced TS cables to RCA.


#5

I think working ITB is coming back to bite me on the arse.
I’m completely bloody confused by all this balanced and unbalanced stuff. Plus TS and TRS.

The things I’ve read seem to suggest that balanced helps to cut down on interference but cannot run long cables; is that right? I was also under the impression that TS and TRS links directly to the cable being balanced or unbalanced. But I think I may be wrong.

How can I tell if my cable is balanced or unbalanced. And if my Digitone has got unbalanced cables, could that be why the interference from the DFAM is so audible?

Help is very much appreciated.

Adam


#6

Any further ideas would be gratefully received.

Cheers


#7

I’m in the music room currently trying to solve this. No reply from Moog yet and, when I record the lips from the DFAM, I can hear the interference distinctly.
Can anyone possibly help out?


#8

Balanced cables do indeed cut down on interference but they also can be used for long cable runs. TS cables are always unbalanced, TRS cables can (sort of) be both.

You can think of it this way. A TRS cable is CAPABLE of carrying a balanced signal (or unbalanced stereo signals), but for it to make any difference both the input and output it is connected too must both support balanced signals.

The inputs of the Digitone are not balanced, nor are the outputs of the DFAM, so its not going to make a difference using a TRS cable or not since neither of those jacks support balanced signals.

Going from your Digitone to your mixer with two TRS cables could for sure cut down on noise, but it will not remove noise from earlier in the chain.


#10

@apmbpm “The interference exists even when the cable is unplugged from the DFAM; simply having the cable in the Digitone is enough.”

This means it doesn’t have anything to do with the DFAM. It’s either the cables going into the Digitone are bad or the inputs from the Digitone are producing the noise.

All inputs have some amount of noise. Your Digitone’s inputs may be faulty or you might just be gain staging incorrectly. As @Chiron said.

"There is a quite high gain on the analog inputs of the Digitone possible. Reducing the input level settings in the Digitone to ~ 30 should give already enough level and could reduce your noise. "

Turn your Digitone inputs down really low and turn the DFAM up all the way, is the noise still a problem?


#11

Yeah turn your Digi inputs down to fifty


#12

Thanks for your help both of you.

Yeah, I’m boosting the signal from the DFAM quite a bit. When the DFAM is at full volume, it is much quieter than the other elements of the track.
The other elements - Octatrack, digitone - are at a volume that registers healthfully on my Allen and Heath DB4. The manual for the mixer suggests that the LEDs should not clip but should be nearly full range. This I manage with those two elements.
When I introduce the DFAM through the Digitone, it often fails to reach halfway on the LEDs, especially if I have the LP filter used on the DFAM. This then leads me to boost the volume on the Digitone inputs to match the other elements. That’s when the interference arrives.
I was wondering if the volume of the DFAM is faulty; is the fact that I need to boost it so much raising the volume of the interference too?
I have tried three different cables. Two of which are Roland cables. I’ve never experienced issues with the cables before.
The other thing I considered was to run the DFAM directly into the mixer. However, is need a TS to RCA cable and cannot find one. I’m guessing that’s because that type of routing isn’t a typical thing to do?

Again, to you both, thanks so much for your help so far.
Adam


#13

Okay, I’ve tried some other things . . .
Taking the cable or if the DFAM and putting it in the Octatrack - interference gone.
Putting back in DFAM - interference back.

Removing the power from the DFAM but leaving the audio cable in - interference remains.

The DFAM seems like the consistent element in this.


#14

dang sounds annoying, and confusing.
You can get TS to RCA cables in some music stores I have a few. They used to be more common because lots of early home recording gear like cassette 4 tracks and stuff used them. The usually come as pairs connected together, with a yellow and red side, but you could just use one side.

You could try using a DI box between the DFAM and whatever else you are plugging it into, and flipping the ground switch. I don’t know if that would help but if you have one lying around, sometimes that has worked for me when there is weird electrical interference sounds.


#15

Mortfell, thanks so much for your help.

Yeah, I’m going slightly crazy with this. I love the DFAM; it’s a great machine but this interference is driving me insane.

I’ve ordered some other cables with the intention of trying a DI box that I’ve got.

Hopefully it’ll work.

Again, sincere thanks for your replies.

Adam


#16

Either a DI box will sort this for you (try also with the ground lift engaged), or I am starting to suspect that your Moog DFAM outputstage has an issue… Contacted Moog support yet?


#17

Yeah.
Have two support emails sitting in their inbox.

I’m hoping the DI works for now but, even if it does work, I’m thinking the DFAM has a slight issue.

I’m having to use a low pass filter on the Octatrack to take the high interference noises out of the sample once I’ve recorded into the OT. There’s something up somewhere.

Really appreciate the help from others though; working in the box for 10 years didn’t prepare you for these kinds of complications.


#18

ITB you have computer issues/glitches, OTB you have noise, interference, crosstalk, ground loops, impedance mismatches… pick your poison :nyan:

And lets not forget the biggest enemy of both: Room acoustics! A source of endless insanity, delusion and grief…


#19

hope it works out!


#20

I’ve discovered the cause . . .
The Arturia Keystep is sending the sync over CV to the DFAM trigger CV in. When I disconnected this, the interference goes away.
Now of course I need to work out the solution.
Ideas?
:thinking:


#21

DI box does it.
Boom.
Finally.
Thanks for the help guys.